Method and Apparatus for Blind Decoding

• US 20090154607A1
• Filed: 06/06/2008
• Published: 06/18/2009
• Est. Priority Date: 12/13/2007
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Nordstrom, Fredrik, Lindoff, Bengt, Kamuf, Matthias
• Granted Patent: US 8,687,745 B2
• Time in Patent Office: Days
• US Class Current: 375/341
• CPC Class Codes: H04L 1/0038 Blind format detection for detection of modulation format H04L27/0012
• CPC Class Codes: H04L 1/0046 Code rate detection or code type detection H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091
• CPC Class Codes: H04L 1/0091 arrangements specific to receivers, e.g. format detection detection of data rate H04L25/0262; detection of coding rate H04L1/0046

Abstract

According to the teachings presented herein, a method and apparatus provide a reduced search space for blindly decoding a message included in a signal received at a communication receiver, where the message has an unknown format. Improving blind detection efficiency in this manner offers numerous advantages, including but not limited to lower power consumption through reduced processing overhead, and lower power consumption through expanded sleep opportunities. As a non-limiting example, the communication receiver comprises a mobile station configured for operation according to Long Term Evolution (LTE) standards, as promulgated by the 3GPP for E-UTRA systems, where the mobile station is configured to reduce a search space of DCI message decoding by determining message format likelihoods and blindly decoding a received DCI message based on the message format likelihoods.

Claims

1. At a communication receiver, a method of blindly decoding a message included in a received signal according to an unknown one of a plurality of possible message formats:

determining message format likelihoods for at least a subset of the possible message formats; and

iteratively blindly decoding the message from the received signal, assuming a different message format in each iteration in an order based on the message format likelihoods.

2. The method of claim 1, wherein determining message format likelihoods for at least a subset of the possible message formats comprises determining which message formats are more likely in a relative sense.

3. The method of claim 2, further comprising determining which message formats are more likely in a relative sense as a function of received signal quality at the communication receiver.

4. The method of claim 2, further comprising determining which message formats are more likely in a relative sense as a function of a communication service configuration of the communication receiver.

5. The method of claim 2, further comprising determining which message formats are more likely in a relative sense as a function of knowledge at the communication receiver about which particular message formats were used in sending one or more prior messages to the communication receiver.

6. The method of claim 1, wherein determining message format likelihoods for at least a subset of the possible message formats comprises, for at least the subset of the possible message formats, determining which message formats are more likely as a function of at least one of a received signal quality at the communication receiver, a communication service configuration of the communication receiver, and knowledge at the communication receiver about which particular message format was used to send a prior message to the communication receiver.

7. The method of claim 6, wherein determining which message formats are more likely comprises determining that higher coding rate message formats are more likely than lower coding rate message formats if received signal quality at the communication receiver is high, and determining that lower coding rate message formats are more likely than higher coding rate message formats if received signal quality at the communication receiver is low.

8. The method of claim 6, wherein determining which message formats are more likely comprises identifying which ones of the possible message formats are characteristically associated with the communication service configuration of the communication receiver.

9. The method of claim 1, wherein determining message format likelihoods for at least a subset of the possible message formats comprises generating a likelihood list that orders message formats according to their relative likelihoods, and wherein iteratively blindly decoding the message from the received signal, assuming a different message format in each iteration in an order based on the message format likelihoods, comprises iteratively blindly decoding the message using a different message format in each of one or more iterations, according to likelihood list order.

10. The method of claim 1, wherein the received signal is a control channel signal and the message comprises downlink control information (DCI) targeted to one in a plurality of communication receivers, including the communication receiver.

11. The method of claim 1, wherein iteratively blindly decoding the message from the received signal, assuming a different message format in each iteration in an order based on the message format likelihoods, comprises iteratively blindly decoding the message using different message format assumptions taken in order of likelihood until the message is successfully decoded, or until a determination is made to end blind decoding attempts.

12. The method of claim 11, further comprising determining to end blind decoding attempts upon reaching a defined limit on the blind decoding attempts, wherein the defined limit is defined based on at least one of a numerical limit on the number of iterations, a numerical limit defined by the number of message formats for which likelihoods are determined, and a time limit defined by processing or signal timing requirements imposed on the communication receiver.

13. The method of claim 11, further comprising, in response to successfully decoding the message, attempting to blindly decode one or more additional messages from the received signal according to the message format likelihoods.

14. The method of claim 13, wherein attempting to blindly decode one or more additional messages from the received signal according to the message format likelihoods includes adjusting the message format likelihoods in view of the message formats of any messages already successfully decoded from the received signal for a same received signal time.

29. The communication receiver of claim 13, wherein the one or more processing circuits comprise a controller configured to determine a likelihood list representing the relative likelihoods for a number of message formats, and a decoder configured to iteratively blindly decode the message.

15. A communication receiver configured to blindly decode a message included in a received signal according to an unknown one of a plurality of possible message formats, said communication receiver comprising one or more processing circuits configured to:

determine message format likelihoods for at least a subset of the possible message formats; and

iteratively blindly decode the message from the received signal, assuming a different message format in each iteration in an order based on the message format likelihoods.

16. The communication receiver of claim 15, wherein the one or more processing circuits are configured to determine the message format likelihoods by determining which message formats are more likely in a relative sense.

17. The communication receiver of claim 16, wherein the one or more processing circuits are configured to determine which message formats are more likely in a relative sense as a function of received signal quality at the communication receiver.

18. The communication receiver of claim 16, wherein the one or more processing circuits are configured to determine which message formats are more likely in a relative sense as a function of a communication service configuration of the communication receiver.

19. The communication receiver of claim 16, wherein the one or more processing circuits are configured to determine which message formats are more likely in a relative sense as a function of knowledge at the communication receiver about which particular message formats were used in sending one or more prior messages to the communication receiver.

20. The communication receiver of claim 15, wherein the one or more processing circuits are configured to determine the message format likelihoods by determining which message formats are more likely as a function of at least one of a received signal quality at the communication receiver, a communication service configuration of the communication receiver, and knowledge at the communication receiver about which particular message format was used to send a prior message to the communication receiver.

21. The communication receiver of claim 20, wherein the one or more processing circuits are configured to determine which message formats are more likely by determining that lower coding rate message formats are more likely than higher coding rate message formats if received signal quality at the communication receiver is low and determining that higher coding rate message formats are more likely than lower coding rate message formats if received signal quality at the communication receiver is high.

22. The communication receiver of claim 20, wherein the one or more processing circuits are configured to determine which message formats are more likely by identifying which ones of the possible message formats are characteristically associated with the communication service configuration of the communication receiver.

23. The communication receiver of claim 15, wherein the one or more processing circuits are configured to determine the message format likelihoods by generating a likelihood list that orders message formats according to their relative likelihoods, and are configured to iteratively blindly decode the message from the received signal by iteratively decoding the message using a different message format assumption in each of one or more iterations, in likelihood list order.

24. The communication receiver of claim 15, wherein the received signal is a control channel signal and the message comprises downlink control information (DCI) targeted to one in a plurality of communication receivers, including the communication receiver.

25. The communication receiver of claim 15, wherein the one or more processing circuits are configured to iteratively blindly decode the message from the received signal by iteratively blindly decoding the message using different message format assumptions taken in order of likelihood until the message is successfully decoded, or until a determination is made to end blind decoding attempts.

26. The communication receiver of claim 25, wherein the one or more processing circuits are configured to end blind decoding attempts upon reaching a defined limit on the blind decoding attempts, wherein the defined limit is defined based on at least one of a numerical limit on the number of blind decoding iterations, a numerical limit defined by the number of message formats for which likelihoods are determined, and a time limit defined by processing or signal timing requirements imposed on the communication receiver.

27. The communication receiver of claim 25, wherein the one or more processing circuits are further configured to, in response to successfully decoding the message, attempt to blindly decode one or more additional messages from the received signal according to the message format likelihoods.

28. The communication receiver of claim 27, wherein the one or more processing circuits are configured to adjust the message format likelihoods in view of the message formats of any messages already successfully decoded from the received signal for a same received signal time.